Dressing sewing thread to reduced friction

ABSTRACT

A dressed sewing thread of reduced friction, preferably comprising polyester, carrying as a non-friction dressing a polycarbonate-polydimethylsiloxane block copolymer comprising about 8 to 35 percent by weight of polycarbonate segments and about 65 to 92 percent by weight of polydimethylsiloxane sements; the polycarbonate segments are preferably of Bisphenol-A. Preferably the dressing also includes a polydiorganosiloxane present in about 2 to 20 times the weight of the block copolymer.

United States Patent 1191 Buchner et a1.

[ DRESSING SEWING THREAD TO REDUCED FRICTION [75] Inventors: WernerBuchner, Leichlingen;

Walter Noll, Opladen; Friedrich Reich, Leverkusen; Wiltried Kortmann,Hohenlimburg; Josef Pfeiffer, Opladen-Quettingen, all of Germany [73]Assignee: Bayer Aktiengesellschaft,

Leverkusen, Germany [22] Filed: Dec. 7, 1972 [21] Appl. No.: 313,075

[30] Foreign Application Priority Data Dec. 16, 1971 Germany 2162417 [52us. c1. 117/1388 F, 117/1383 N, 117/138.8 VA, 117/1395 A,

117/161 ZA [51] Int. Cl. D06m 15/66, ClOm 3/44 [58'] Fieldot Search. ..117/138.8 F, 1395 A, 139.5 c, 117/1395 0; 260/824 R, 46.5 R

[56] References Cited UNITED STATES PATENTS 2,597,614 5/1952 Brown eta1. 117/139.5 X 2,872,356 2/1959 Bull et al. 117/1395 3,189,662 6/1965Vaughn 260/824 3,271,189 9/1966 Hofmann 117/138.8 3,423,235 1/1969Campbell 117/1395 X Primary ExaminerHerbert B. Guynn Attorney, Agent, orFirm-Burgess, Dinklage & Sprung [5 7] ABSTRACT 5 Claims, No DrawingsDRESSING SEWING THREAD TO REDUCED FRICTION This invention relates to aprocess for the dressing of sewing thread, in particular polyesterthread, for the purpose of reducing its friction produced when sewing.

Dressing agents of this kind are already known and the substances usedmay be e.g., polydiorganosiloxane oils or a mixture of these oils andpolyethylene waxes. Hydrocarbon-siloxane copolyners are also known toreduce friction.

in which n is an integer of about to 90 with ana,w-dihydroxypolycarbonate of the following formula,

which XP' bfitsihs a msaninsiasa lq s;

These finishes are preferably applied to the threads from aqueousemulsions or as a mixture of siloxane and waxes which are free fromsilicon.

Although a sewing thread treated with the known antifriction agentsreduces the friction produced when sewing, compared to an untreatedthread, the friction produced is still so high that if these threads areused in a sewing machine operating at a high speed they frequentlybreak, causing considerable trouble in the sew-' ing process. Thisbreaking of the thread is due to the inadequate lubricating effect ofthe usual lubricating dressing agents and to their uneven distributionover r s -1Q (RI/)n (HI/) (RI/)3 in which each R independently is ahydrogen atom or an optionally inertly substituted monovalent aliphatic,cycloaliphatic, araliphatic or aromatic hydrocarbon radical having oneto 12 carbon atoms,

eachR." independently is a halogen atom or an alkyl radical having oneto four carbon atoms,

p is an integer of from 1 to 7, and

a is zero or an integer of from 1 to 4, and about 65 to 92 percent byweight of polydimethylsiloxane segments having an average chain lengthof about 15 to 90 dimethylsiloxane units, the individual segments beinglinked via aryl-O-Si bonds (Component B), which solution or emulsion mayalso contain polydiorganosiloxanes having a viscosity of about 500 to20,000 cP, preferably about 1000 to 10,000 cPat 20C (Component A).

According to the proposal disclosed in the copending application Ser.No. 313,073, filed Dec. 7, 1972, entitledPolydiorganosiloxane-Polycarbonate Block Copolymers" and assigned to thesame assignee, the polycarbonate-polydimethylsiloxane block copolymersmay be prepared by reacting an a,w-dichloropolydimethylsiloxane of theformula R! R a O C Sl a an. I II J I C R in the presence of a tertiaryamine. The process is carried out by reacting 1 mole of thea,w-dihydroxypolycarbonate dissolved in an inert organic solvent withabout 0.5 to 5 moles of the a,w-dichloropolydimethylsiloxane in thepresence of a quantity of tertiary amine which is stoichiometricallyequivalent to the chlorine content of thea,w-dichloropolydimethylsiloxane and then heating the reaction mixtureto a temperature of about 60C to 100C and isolating the reaction productby filtering off the amine salt and removing the solvent.

The polycarbonates with terminal hydroxyl groups to be used according tothe invention preferably have a chain length of about 2 to 5diphenylalkane units and may be derived from any bis-phenols. In theformulae shown above, R may represent e.g., a methyl, ethyl, propyl,isopropyl, butyl, isobutyl or tertiary butyl radical or a chlorine,bromine or iodine atom; R, which may include inert substituents, ispreferably a hydrocarbon radical such as an alkyl radical, e.g., methyl,ethyl, propyl or butyl, an alkenyl radical, e.g., vinyl, a cycloalkyl orhaloalkyl radical, e.g., chlorobutyl or cyclohexyLa substituted orunsubstituted aryl radical, e.g., phenyl, chlorophenyl, xylyl or tolyl,or an araliphatic radical such as phenylethyl or benzyl. It is preferredto use the polycarbonate derived from 2,2-bis(phydroxyphenyl)-propane(Bisphenol-A), i.e., the polycarbonate in which R CH a 0 and p 2 to 4.

Other bis-phenols suitable for the preparation of polycarbonates havebeen described e.g., in US. Pat. Nos. 3,028,365; 2,999,835; 3,148,172;3,271,368; 2,970,137; 2,991,273; 3,271,367; 3,014,891 and 2,999,846.

Block copolymers obtained by the process according to US. Pat. No.3,189,662, for example, are also suitable for the process according tothe invention.

The polydiorganosiloxanes (Component A) which are optionally added tothe solution or emulsion may be obtained by known methods. Suitablepolydiorganosiloxanes are e.g., polydialkylsiloxanes or alsopolydiorganosiloxanes which contain dialkylsiloxy groups anddiarylsiloxy groups statistically distributed. Polydimethylsiloxane ispreferred.

The quantity of polydiorganosiloxanes added may vary within a widerange. Preferably, about parts by weight of A are added to 5 to 50 partsby weight of Component B.

According to the invention, the polycarbonatepolydimethylsiloxane blockcopolymers are applied to the thread from a solution or emulsion. If theblock copolymer is to be applied from solution, a 3 to 40 percent byweight solution is prepared to which varying v quantities of Component Amay be added.

According to a preferred embodiment of the process, about 150 to 180 gof A are used for every 26 to 32 g of B, together with the amount ofsolvent needed to produce a 16 to 20 percent solution. The solvent used,for example, may be trichloroethylene, perchloroethylene, methylchloroform, chlorobenzene or a mixture thereof.

If the dressing agent is to be applied to the sewing thread from anemulsion, a solution of component B or of components A and B in anon-polar solvent such as toluene, xylene, petroleum hydrocarbons ormixtures of such solvents with trichloroethylene or perchloroethylene isfirst prepared. This solution is then emulsi fied in water in the usualmanner with the addition of a conventional stabilizing agent, preferablya commercial partly hydrolyzed polyvinyl acetate, hereinafter brieflyreferred to as polyvinyl alcohol, and optionally with the addition of anethoxylated alcohol. The proportions of the different components are sochosen that the emulsion contains about 30 to 40 percent by weight of Bor of A B. If a mixture of A B is used, it has been found preferable touse the components in proportions, by weight. of about 25 to 30 parts ofA, about 7 to 11 parts of B, about 2 to 3 parts of polyvinyl alcohol,about 21 to 24 parts of solvent and about 35 to 40 parts of water.

The sewing threads are dressed by the process according to the inventione.g., by bringing them into contact with the emulsion or solution ofcomponent B or of a mixture of A B by a rewinding process using a driveroller and then drying them by heating to about 80 to 100C. Sewingthreads which have been dressed by the process according to theinvention, in particular polyester sewing threads, have the advantageover sewing threads dressed by known methods that they have lowercoefficients of friction, which are a measure of the friction produced.In addition, the dressings are more evenly distributed over the surfaceof the thread, as determined by the range of scatter of the coefficientof friction. Sewing can therefore be carried at higher speeds with suchthreads. The essential properties which determine the sliding of asewing thread, namely its coefficient of friction, and the scatter rangeof friction, are determined by means of a friction measuring devicecalled F meter and made by Rothschild, Zurich, at 20C/65 percentrelative humidity applying a preliminary tension of g (see e.g. MelliandTextilberichte 42 1961 374-3 79). The quantity of dressing applied ispreferably from about 1 to 7 percent, especially about 3 to 5 percent byweight, based on the sewing thread although quantities above or belowthis range may be used.

The process according to the invention will now be explained more fullywith reference to the following examples in which, in all cases,percentages refer to percentages by weight.

EXAMPLE 1 An emulsion is prepared by first mixing 68.4 g of a with thisemulsion has a coefficient of friction of 1.0

and a range of scatter of friction of between 14 and 18 g; the yarncarried 4 percent of solids by weight.

If for the purpose of comparison with conventional emulsions the 24 g ofpolycarbonate-polysiloxane block copolymers used in the above exampleare replaced by the corresponding quantity of polydimethylsiloxanehaving a viscosity of 10,000 cP at 20C, i.e., if the process is carriedout without the block copolymer B, the sewing threads obtained have acoefficient of friction of 3.0 and a range of scatter of between 40 and75.

EXAMPLE 2 This example demonstrates the relationship between the slidingproperties of sewing threads and the quantity of components B when thetotal quantity of (A B) in the emulsion is kept constant, thecomposition of the emulsion being otherwise the same as in Example 1.The results given in Example 1 have been repeated here for clarity.

No. Quantity Quantity Coefficient Range of of A of B of scatter g gfriction g l 80 0 3.0 40-75 2 72 8 1.7 20-32 3 68 12 1.2 16.22 4 6O 2()1.1 18-22 5 56 24 1.0 l4-l8 EXAMPLE 3 When a solution of 15 g of apolycarbonatepolysiloxane block copolymer consisting of 27.8 percent byweight of Bisphenol-A polycarbonate segments and 72.7 percent by weightof polydimethyl siloxane segments having an average chain length of 29is emulsifted in 108 g of water as described in Example 1 together with70 g of polydimethylsiloxane (10,000 cP/20C) in 35 g of toluene and 10 gof perchloroethylene with 6.5 g of polyvinyl alcohol and the resultingemulsion is used as a dressing agent forthe sewing thread of Example 1,the following values are obtained:

Coefficient of friction Range of scatter of friction EXAMPLE 4 If inemulsion No. 3 of Example 2 the polydimethylsiloxane which has aviscosity of 10,000 cP at 20C is replaced by one having a viscosity of1000 cP at 20C and the sewing thread of Example 1 dressed with such anemulsion are compared with threads treated with an of a paraffin waxwhich has a melting point of 82C and emulsion which contains only thepolydimethylsiloxane 20 parts by weight of a ol ydimethylsiloxane whichhas which has a viscosity of 1000 cP, the following results a isc ity of1000 CP 20 thelhfeflds are fOund I are obtained: have a coefficient offriction of 2.5 and a range of scatter of 35 to 50 g.

The polyester fibers employed in the foregoing examfjg g ff g g f l gf fples were polyethylene terephthalate but other polyesg g friction A gters falling within the definition of that term as set forth in theRules promulgated under the Textile Fibers iden- 33 if; tification Actcan be similarly treated with similar effect. The yarns may be 100percent polyester or blends thereof with other natural and/or man-madefibers, ei-

EXAMPLE 5 ther in staple or filament form. While polyesters are ThisExample was carried Out using n emulsion preferred, the invention isalso applicable to polyesterwhich contained only apolycarbonate-polysiloxane l 5 free yams uch 35 nylon, acrylics, and thelike,

block copolymer nd n i y y)- it will be appreciated that the instantspecification polydimethylsiloxane. A solution of 39 g of the block dexamples are t f th b w f ill tr ti d copolymer described in Example 1in 25 g of toluene not limitation, and that various modifications andand 4.3 g of perchloroethylene was emulsified in 30.3 changes may bemade without departing from the spirit g 0f water With the addition Of2.7 g Of polyvinyl alcoand cope of the present invention,

hol and the emulsion was then diluted with 14 g of wawh t i l i d iter. 1. A low-friction sewing thread dressed with a polyc- The Sewingthread of Example 1 dressed with this arbonate-polydimethylsiloxaneblock copolymer comemulsion was found to have a coefficient of frictionof prising about 8 to 35 percent by weight of polycarbon- 0.09 with arange of scatter of friction of 12 to 14 g. t Segments f th f l EXAMPLE6 in which The sewing thread of Example I treated with a solueach Rindependently is a hydrogen atom or a mondtion P trichloroethylene) of ablock 00- valent aliphatic, cycloaliphatic. araliphatic or aromaticpolymer of 13.8 percent of Bisphenol-A polycarbonate hydrocarbon radicalwith l to 12 carbon atoms, segments having an average chain length f 2.7a d each R independently is a lower alkyl radical or a 86.2 percent ofpolydimethyl-siloxane segments having hal at an average chain length of77 was found to have a coefficient of friction of 0.07 and a range ofscatter of friction of between 12 and 14 g.

p is an integer from i to 7 and 40 a is an integer from 0 to 4,

and about 6 5 to 02 percent by weight ofpolydimethyl- EXAMPLE 7 siloxanesegments having an average chain length of A polyester filament yarndressed with a trichloroethabout to 90 dlmethylslloxane unitsylenesolution which contained 165 g of a siloxane A (viscosity 20,000 cP/20C) in addition to 29 g of the 7% of solids by weight. block copolymefrmennoned m Example 5 and m much 3. The thread of claim 2, wherein thesolids include zoncegtratlon i 9 g g g a polydiorganosiloxane having aviscosity of about 500 to f CO6 Clem O a to 20,000 cP at 20C, about5 toparts by weight of gg g ig gs igg gi x 9 and 23 50 said block copolymerbeing present per 100 parts of z l l l If, in Example 1, the blockcopolymer B is replaced gzgigtiz gi gifi wherein is methyl p is i r 1 11 9 1 by the corresponding quanitiy of a paraffin wax and the about 2 to5, a is O, and the polydiorganosfloxane is same sewin threads aredressed with this emulsion, the threads are found to have a coefficientof friction of 2.8 polydimethylslloxane having a vlscoslty of about1,000

to 10,000 cP at 20C.

and a range of scatter of 45 to g.

2. The sewing thread of claim 1, carrying about l to ComparisonExperiment: 5. The thread of claim 4, wherein said sewing thread Whenthe same sewing threads are not dressed with comprlses p y l V ,mo. o* man emulsion but with a mixture of 80 parts by weight l k

1. A LOW-FRICTION SEWING THREAD DRESSED WITH APOLYCARBONATE-POLYDIMETHYLSILOXANE BLOCK COPOLYMER COMPRISING ABOUT 8 TO35 PERCENT BY WEIGHT OF POLYCARBONATE SEGMENTS OF THE FORMULA
 2. Thesewing thread of claim 1, carrying about 1 to 7% of solids by weight. 3.The thread of claim 2, wherein the solids include a polydiorganosiloxanehaving a viscosity of about 500 to 20,000 cP at 20*C, about 5 to 50parts by weight of said block copolymer being present per 100 parts ofsaid polydiorganosiloxane.
 4. The thread of claim 3, wherein R'' ismethyl, p is about 2 to 5, a is 0, and the polydiorganosiloxane ispolydimethylsiloxane having a viscosity of about 1,000 to 10,000 cP at20*C.
 5. The thread of claim 4, wherein said sewing thread comprisespolyester.